Enhance Mandibular Symphyseal Surface Bone Growth with Autologous Mesenchymal Stem Cell Sheets: An Animal Study.

[INTRODUCTION] The size and shape of the chin strongly influence facial profile and harmony. The current correction of chin deficiency mostly relies on genioplasty surgery involving osteotomy. To avoid osteotomy, one possible alternative is to enhance bone growth at the mental protuberance area with cell sheet transplantation. This study was undertaken to evaluate the efficacy of this approach in a pig model.

[MATERIALS AND METHODS] Five 4-month-old pigs were included for mandibular bone marrow aspiration and MSC isolation. Triple-layer MSC sheets were then fabricated and utilized using culture-expanded MSCs. Four weeks after bone marrow aspiration, subperiosteal pockets were created on the labial symphyseal surface, followed by transplantation of autogenous MSC sheets to one randomly chosen side with the other side (control) receiving no transplantation. Six weeks after the surgery, the pigs were euthanized and the specimens from both sides were collected for computed tomography (CT) and histological and immunohistochemical analysis. Measurements between the experimental and control sides were compared using paired t tests.

[RESULTS] MSC sheet fabrication and transplantation were reliably conducted. The labial cortical bone thickness increased significantly with MSC sheet transplantation by an average of 2 mm (p = 0.0001). The average measurements of mineral apposition rate and cell proliferation at the cell sheet side tended to be higher than the control side although the differences did not reach statistical significance (p = 0.1-0.2). Tissue mineral density measurements from CT images and bone volume fraction (BV/TV) measurements from histologic images were identical between the two sides (p > 0.5).

[CONCLUSION] These data provide a proof of concept that autologous MSC sheets may be transplanted to the subperiosteal region of the mandibular symphysis to stimulate local surface bone growth.

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